[log in to unmask]: in response to ur earlier e-mail regarding above subject, u r definitely right and to put it correctly - not clear on the issue.( pun ) when the tin bath oxidizes for whatever reason and turns into stannic - the grain refiner and wetters are what suspend the stannic colloid in solution - oxidization of the solution is inevitable - that is the nature of tin. when these tin colloids accumulate not only will they co-deposit but the concentration of the colloids eventually accumulate causing an overall deficiency of the process. filtration by itself will do nothing - the colloids must be clarified from solution - coagulated - settled then if u want to filter - u can - but - there will be enough coagualted stannic at the bottom of the bath that u can actually scoop out with a shovel.if this is not done periodically as a maitenance procedure - eventually there will be enough suspended tin colloids and breakdown product - that it just might cost u more to clean it up than replace it and wastetreat the existing process. the clarifier that we manufacture ( ATOTECH CANADA ) is the trick to the whole process. the clarifier enables our customers to clean out their existing stannous sulfate processes in about eight hours time - analyze the process - and it's good as new!! we have over 20,000 gallons of tin in operation in Canada - so we see samples of these baths every week. a stannous sulfate process is still less expensive to install, operate and maintain. changing over from solder to tin is also beneficial in reducing sludge in the tin stripper. there will be enough of a deposit of tin in a 6 to 7 minute period to act as a decent metallic etch resist. [log in to unmask] Atotech Canada - providing quality products and services that meet our customers expectations